Individuals with high bone mass have increased progression of radiographic and clinical features of knee osteoarthritis

OBJECTIVE

High bone mass (HBM) is associated with an increased prevalence of radiographic knee OA (kOA), characterized by osteophytosis. We aimed to determine if progression of radiographic kOA, and its sub-phenotypes, is increased in HBM and whether observed changes are clinically relevant.

DESIGN

A cohort with and without HBM (L1 and/or total hip bone mineral density Z-score≥+3.2) had knee radiographs collected at baseline and 8-year follow-up. Sub-phenotypes were graded using the OARSI atlas. Medial/lateral tibial/femoral osteophyte and medial/lateral joint space narrowing (JSN) grades were summed and Δosteophytes, ΔJSN derived. Pain, function and stiffness were quantified using the WOMAC questionnaire. Associations between HBM status and sub-phenotype progression were determined using multivariable linear/poisson regression, adjusting for age, sex, height, baseline sub-phenotype grade, menopause, education and total body fat mass (TBFM). Generalized estimating equations accounted for individual-level clustering.

RESULTS

169 individuals had repeated radiographs, providing 330 knee images; 63% had HBM, 73% were female, mean (SD) age was 58 (12) years. Whilst HBM was not clearly associated with overall Kellgren-Lawrence measured progression (RR = 1.55 [0.56.4.32]), HBM was positively associated with both Δosteophytes and ΔJSN individually (adjusted mean differences between individuals with and without HBM 0.45 [0.01.0.89] and 0.15 [0.01.0.29], respectively). HBM individuals had higher WOMAC knee pain scores (β = 7.42 [1.17.13.66]), largely explained by adjustment for osteophyte score (58% attenuated) rather than JSN (30% attenuated) or TBFM (16% attenuated). The same pattern was observed for symptomatic stiffness and functional limitation.

CONCLUSIONS

HBM is associated with osteophyte progression, which appears to contribute to increased reported pain, stiffness and functional loss.

Combining genomewide association study and lung eQTL analysis provides evidence for novel genes associated with asthma

BACKGROUND

Genomewide association studies (GWASs) of asthma have identified single-nucleotide polymorphisms (SNPs) that modestly increase the risk for asthma. This could be due to phenotypic heterogeneity of asthma. Bronchial hyperresponsiveness (BHR) is a phenotypic hallmark of asthma. We aim to identify susceptibility genes for asthma combined with BHR and analyse the presence of cis-eQTLs among replicated SNPs. Secondly, we compare the genetic association of SNPs previously associated with (doctor's diagnosed) asthma to our GWAS of asthma with BHR.

METHODS

A GWAS was performed in 920 asthmatics with BHR and 980 controls. Top SNPs of our GWAS were analysed in four replication cohorts, and lung cis-eQTL analysis was performed on replicated SNPs. We investigated association of SNPs previously associated with asthma in our data.

RESULTS

A total of 368 SNPs were followed up for replication. Six SNPs in genes encoding ABI3BP, NAF1, MICA and the 17q21 locus replicated in one or more cohorts, with one locus (17q21) achieving genomewide significance after meta-analysis. Five of 6 replicated SNPs regulated 35 gene transcripts in whole lung. Eight of 20 asthma-associated SNPs from previous GWAS were significantly associated with asthma and BHR. Three SNPs, in IL-33 and GSDMB, showed larger effect sizes in our data compared to published literature.

CONCLUSIONS

Combining GWAS with subsequent lung eQTL analysis revealed disease-associated SNPs regulating lung mRNA expression levels of potential new asthma genes. Adding BHR to the asthma definition does not lead to an overall larger genetic effect size than analysing (doctor's diagnosed) asthma.

The independent role of prenatal and postnatal exposure to active and passive smoking on the development of early wheeze in children

Maternal smoking during pregnancy increases childhood asthma risk, but health effects in children of nonsmoking mothers passively exposed to tobacco smoke during pregnancy are unclear. We examined the association of maternal passive smoking during pregnancy and wheeze in children aged ≤2 years.Individual data of 27 993 mother-child pairs from 15 European birth cohorts were combined in pooled analyses taking into consideration potential confounders.Children with maternal exposure to passive smoking during pregnancy and no other smoking exposure were more likely to develop wheeze up to the age of 2 years (OR 1.11, 95% CI 1.03-1.20) compared with unexposed children. Risk of wheeze was further increased by children's postnatal passive smoke exposure in addition to their mothers' passive exposure during pregnancy (OR 1.29, 95% CI 1.19-1.40) and highest in children with both sources of passive exposure and mothers who smoked actively during pregnancy (OR 1.73, 95% CI 1.59-1.88). Risk of wheeze associated with tobacco smoke exposure was higher in children with an allergic versus nonallergic family history.Maternal passive smoking exposure during pregnancy is an independent risk factor for wheeze in children up to the age of 2 years. Pregnant females should avoid active and passive exposure to tobacco smoke for the benefit of their children's health.

Pet ownership is associated with increased risk of non-atopic asthma and reduced risk of atopy in childhood: findings from a UK birth cohort

BACKGROUND

Studies have shown an inverse association of pet ownership with allergy but inconclusive findings for asthma.

OBJECTIVE

To investigate whether pet ownership during pregnancy and childhood was associated with asthma and atopy at the age of 7 in a UK population-based birth cohort.

METHODS

Data from the Avon Longitudinal Study of Parents and Children (ALSPAC) were used to investigate associations of pet ownership at six time points from pregnancy to the age of 7 with asthma, atopy (grass, house dust mite, and cat skin prick test) and atopic vs. non-atopic asthma at the age of 7 using logistic regression models adjusted for child's sex, maternal history of asthma/atopy, maternal smoking during pregnancy, and family adversity.

RESULTS

A total of 3768 children had complete data on pet ownership, asthma, and atopy. Compared with non-ownership, continuous ownership of any pet (before and after the age of 3) was associated with 52% lower odds of atopic asthma [odds ratio (OR) 0.48, 95% CI 0.34-0.68]. Pet ownership tended to be associated with increased risk of non-atopic asthma, particularly rabbits (OR 1.61, 1.04-2.51) and rodents (OR 1.86, 1.15-3.01), comparing continuous vs. non-ownership. Pet ownership was consistently associated with lower odds of sensitization to grass, house dust mite, and cat allergens, but rodent ownership was associated with higher odds of sensitization to rodent allergen. Differential effects of pet ownership on atopic vs. non-atopic asthma were evident for all pet types.

CONCLUSIONS AND CLINICAL RELEVANCE

Pet ownership during pregnancy and childhood in this birth cohort was consistently associated with a reduced risk of aeroallergen sensitization and atopic asthma at the age of 7, but tended to be associated (particularly for rabbits and rodents) with an increased risk of non-atopic asthma. The opposing effects on atopy vs. non-atopic asthma might be considered by parents when they are deciding whether to acquire a pet.

Maternal 25-hydroxyvitamin D and its association with childhood atopic outcomes and lung function

Background

It has been suggested that maternal vitamin D status in pregnancy influences the risk of asthma and atopy in the offspring. The epidemiological evidence to support these claims is conflicting and may reflect chance findings and differences in how vitamin D was assessed.

Objective

To examine the association between blood total maternal 25-hydroxy vitamin D (25(OH)D) concentrations in pregnancy and offspring asthma, atopy and lung function in the largest birth cohort study to date.

Methods

Participants were largely of white European origin and resident in the South West of England. We examined the associations of maternal 25(OH)D concentrations in pregnancy with the following outcomes in the offspring: wheeze, asthma, atopy, eczema, hayfever, at mean age 7.5 years (n = 3652–4696 depending on outcome), IgE at 7 years (n = 2915) and lung function and bronchial responsiveness at mean age 8.7 years (n = 3728–3784).

Results

Sixty-eight per cent of mothers had sufficient (> 50 nmol/L) concentrations of 25(OH)D, 27% were insufficient (27.5–49.99 nmol/L) and 5% were deficient (< 27.5 nmol/L). There was no evidence to suggest that maternal 25(OH)D concentration in pregnancy was associated with any respiratory or atopic outcome in the offspring. These findings remained after adjustment for season of measurement and for potential confounders. There was also no evidence that these relationships followed a non-linear form and no evidence that either deficient or high concentrations of maternal 25(OH)D were associated with atopic or respiratory outcomes.

Conclusions

We found no evidence that maternal blood 25(OH)D concentration in pregnancy is associated with childhood atopic or respiratory outcomes.

Genome-wide association study of body mass index in 23 000 individuals with and without asthma

BACKGROUND

Both asthma and obesity are complex disorders that are influenced by environmental and genetic factors. Shared genetic factors between asthma and obesity have been proposed to partly explain epidemiological findings of co-morbidity between these conditions.

OBJECTIVE

To identify genetic variants that are associated with body mass index (BMI) in asthmatic children and adults, and to evaluate if there are differences between the genetics of BMI in asthmatics and healthy individuals.

METHODS

In total, 19 studies contributed with genome-wide analysis study (GWAS) data from more than 23 000 individuals with predominantly European descent, of whom 8165 are asthmatics.

RESULTS

We report associations between several DENND1B variants (P = 2.2 × 10(-7) for rs4915551) on chromosome 1q31 and BMI from a meta-analysis of GWAS data using 2691 asthmatic children (screening data). The top DENND1B single nucleotide polymorphisms(SNPs) were next evaluated in seven independent replication data sets comprising 2014 asthmatics, and rs4915551 was nominally replicated (P < 0.05) in two of the seven studies and of borderline significance in one (P = 0.059). However, strong evidence of effect heterogeneity was observed and overall, the association between rs4915551 and BMI was not significant in the total replication data set, P = 0.71. Using a random effects model, BMI was overall estimated to increase by 0.30 kg/m(2) (P = 0.01 for combined screening and replication data sets, N = 4705) per additional G allele of this DENND1BSNP. FTO was confirmed as an important gene for adult and childhood BMI regardless of asthma status.

CONCLUSIONS AND CLINICAL RELEVANCE

DENND1B was recently identified as an asthma susceptibility gene in a GWAS on children, and here, we find evidence that DENND1B variants may also be associated with BMI in asthmatic children. However, the association was overall not replicated in the independent data sets and the heterogeneous effect of DENND1B points to complex associations with the studied diseases that deserve further study.

Glutathione-S-transferase P1, early exposure to mould in relation to respiratory and allergic health outcomes in children from six birth cohorts. A meta-analysis

BACKGROUND

There are conflicting study results regarding the association of exposure to visible mould and fungal components in house dust with respiratory and allergic diseases in children. It has been suggested that functional polymorphisms of the GSTP1 gene may influence the risk for allergic disorders through an impaired defence against oxidant injury.

METHODS

We examined in six birth cohorts of over 14 000 children whether the association between early exposure to reported mould at home in relation to respiratory and allergic diseases is modified by a single nucleotide polymorphism of the GSTP1 gene.

RESULTS

We observed a positive association of mould exposure with nasal symptoms (2-10 year) aOR: 1.19 (1.02-11.38). Further, there was a borderline significant increased risk of rhinoconjunctivitis (6-8 year) in children homozygous for the minor allele Val/Val, aOR: 1.25 (0.98-1.60). In stratified analyses, subjects homozygous for the minor allele and exposed to mould at home were at increased risk for early wheezing aOR: 1.34 (1.03-1.75), whereas the major allele may confer susceptibility for later nasal outcomes, (6-8 year) aOR: 1.20 (1.00-1.45) and (2-10 year) aOR: 1.30 (1.04-1.61), respectively. For none of the health outcomes studied, we found gene by environment interactions.

CONCLUSION

A genetic influence of the GSTP1 gene cannot be ruled out, but the magnitude of the effect is a matter of further research. In conclusion, the interplay between gene and environments is complex and remains subject of further study.

Meta-analysis of mould and dampness exposure on asthma and allergy in eight European birth cohorts: an ENRIECO initiative

BACKGROUND

Several cross-sectional studies during the past 10 years have observed an increased risk of allergic outcomes for children living in damp or mouldy environments.

OBJECTIVE

The objective of this study was to investigate whether reported mould or dampness exposure in early life is associated with the development of allergic disorders in children from eight European birth cohorts.

METHODS

We analysed data from 31 742 children from eight ongoing European birth cohorts. Exposure to mould and allergic health outcomes were assessed by parental questionnaires at different time points. Meta-analyses with fixed- and random-effect models were applied. The number of the studies included in each analysis varied based on the outcome data available for each cohort.

RESULTS

Exposure to visible mould and/or dampness during first 2 years of life was associated with an increased risk of developing asthma: there was a significant association with early asthma symptoms in meta-analyses of four cohorts [0-2 years: adjusted odds ratios (aOR), 1.39 (95% CI, 1.05-1.84)] and with asthma later in childhood in six cohorts [6-8 years: aOR, 1.09 (95% CI, 0.90-1.32) and 3-10 years: aOR, 1.10 (95% CI, 0.90-1.34)]. A statistically significant association was observed in six cohorts with symptoms of allergic rhinitis at school age [6-8 years: aOR, 1.12 (1.02-1.23)] and at any time point between 3 and 10 years [aOR, 1.18 (1.09-1.28)].

CONCLUSION

These findings suggest that a mouldy home environment in early life is associated with an increased risk of asthma particularly in young children and allergic rhinitis symptoms in school-age children.

Associations of wheezing phenotypes in the first 6 years of life with atopy, lung function and airway responsiveness in mid-childhood

Background:

Patterns of wheezing during early childhood may indicate differences in aetiology and prognosis of respiratory illnesses. Improved characterisation of wheezing phenotypes could lead to the identification of environmental influences on the development of asthma and airway diseases in predisposed individuals.

Methods:

Data collected on wheezing at seven time points from birth to 7 years from 6265 children in a longitudinal birth cohort (the ALSPAC study) were analysed. Latent class analysis was used to assign phenotypes based on patterns of wheezing. Measures of atopy, airway function (forced expiratory volume in 1 s (FEV₁), mid forced expiratory flow (FEF_25-75)) and bronchial responsiveness were made at 7–9 years of age.

Results:

Six phenotypes were identified. The strongest associations with atopy and airway responsiveness were found for intermediate onset (18 months) wheezing (OR for atopy 8.36, 95% CI 5.2 to 13.4; mean difference in dose response to methacholine 1.76, 95% CI 1.41 to 2.12 %FEV₁ per μmol, compared with infrequent/never wheeze phenotype). Late onset wheezing (after 42 months) was also associated with atopy (OR 6.6, 95% CI 4.7 to 9.4) and airway responsiveness (mean difference 1.61, 95% CI 1.37 to 1.85 %FEV₁ per μmol). Transient and prolonged early wheeze were not associated with atopy but were weakly associated with increased airway responsiveness and persistent wheeze had intermediate associations with these outcomes.

Conclusions:

The wheezing phenotypes most strongly associated with atopy and airway responsiveness were characterised by onset after age 18 months. This has potential implications for the timing of environmental influences on the initiation of atopic wheezing in early childhood.

Can biochemical markers serve as surrogates for imaging in knee osteoarthritis?

OBJECTIVE

Osteoarthritis (OA) is a complex heterogeneous joint disease affecting more than 35 million people worldwide. The current gold standard diagnostic investigation is the plain radiograph, which lacks sensitivity. Biochemical markers have the potential to act as adjunct markers for imaging in the assessment of knee OA. We undertook this study to determine the association between individual biochemical markers and radiographic features, and to establish whether the association is strengthened when selected biochemical markers are combined into a single factor (a theoretical marker).

METHODS

Twenty serum and urinary biochemical markers were analyzed in 119 patients with predominantly tibiofemoral knee OA. Pearson's correlation was performed, and corresponding coefficients of determination (R(2)) were calculated to determine the association between biochemical markers and a range of imaging features from radiographs and dual x-ray absorptiometry of the knee. Biochemical markers demonstrating a significant association (P < 0.05) with a specific imaging feature were combined by principal components analysis (PCA). Pearson's correlation was repeated to establish whether the combined panel of biochemical markers showed a stronger association with imaging than the best single marker.

RESULTS

Fourteen biochemical markers showed significant associations with one or more imaging features. By combining specific panels of biochemical markers to form factors, the association of markers with imaging features (R(2)) increased from 11.9% to 22.7% for the Kellgren/Lawrence (K/L) score, from 5.9% to 9.2% for joint space width (JSW), from 6.6% to 10.8% for sclerosis, from 13.5% to 22.6% for osteophytes, and from 12.0% to 14.2% for bone mineral density (BMD). Biochemical markers identifying patients with osteophytes overlapped with those correlated with a high K/L score, while markers of subchondral BMD formed a completely separate group. Biochemical markers of JSW included markers associated with both osteophytes and BMD.

CONCLUSION

The PCA results suggest that biochemical marker combinations may be more sensitive than individual biochemical markers for reflecting structural damage in patients with knee OA. The differences in biochemical marker profiles associated with osteophytes compared with those associated with subchondral BMD raise the possibility that these 2 processes, commonly seen in bone in knee OA, have underlying biologic differences.

The association between mother and child MTHFR C677T polymorphisms, dietary folate intake and childhood atopy in a population-based, longitudinal birth cohort

BACKGROUND

A recent study suggested a link between folate metabolism and atopy, based on a positive association between a common polymorphism of the methylenetetrahydrofolate reductase (MTHFR) gene and allergic sensitization in Danish adults.

OBJECTIVE

We investigated the associations between MTHFR C677T and allergy or atopy in a large, population-based birth cohort of children and their mothers, the Avon Longitudinal Study of Parents and Children (ALSPAC). We also looked for evidence of a pre-natal effect of maternal folate metabolism on subsequent atopic disease in the offspring.

METHODS

Mothers were recruited in pregnancy and the children followed from birth. Atopy in the child was assessed at 7-8 years of age by skin prick tests to common allergens. Asthma was defined as a physician diagnosis and current symptoms at 71/2 years of age. Asthma and allergy status of the mothers were obtained from self-completion questionnaires.

RESULTS

Data on MTHFR C677T genotype and allergy were available for 5364 children and on allergy and/or asthma for 7356 mothers. In children, the prevalence of atopy was 20.0% and asthma 10.0% whereas in mothers, the prevalence of self-reported allergy was 42.7% and asthma 11.5%. Atopy in the child was associated with male gender (P<0.001), less tobacco smoke exposure and higher maternal education. MTHFR C677T genotype was not associated with social factors or dietary folate intake. We found no evidence of associations between the MTHFR C677T variant allele and atopy, allergy or asthma in mothers or children. There was no evidence to support an effect of maternal MTHFR C677T genotype on atopy in the offspring.

CONCLUSION

The results of this study do not support the hypothesis that impaired folate metabolism is associated with allergy in adults or children in this population.

Serum cartilage oligomeric matrix protein and other biomarker profiles in tibiofemoral and patellofemoral osteoarthritis of the knee

OBJECTIVES

There is some evidence that tibiofemoral osteoarthritis (TFJ OA) and patellofemoral osteoarthritis (PFJ OA) may have different risk factors. To investigate the possibility that these conditions are separate disease entities, we compared biomarker profiles of patients with each disease.

METHODS

Serum samples were taken from 222 patients who had knee pain and X-ray signs of knee OA. Eighty-two had only medial TFJ OA and 38 only PFJ OA in one or both knees. The remaining patients had either mixed disease or equivocal radiographic evidence of OA. The following biomarkers were measured in serum samples from baseline and follow-up visits: cartilage oligomeric matrix protein (COMP), glycosaminoglycan, keratan sulphate epitope 5D4, YKL-40, osteocalcin, C-telopeptide of type I collagen, hyaluronan and C-reactive protein.

RESULTS

The two subsets of OA (TFJ and PFJ) had similar radiographic disease severity and there were no significant differences in the presence and patterns of pain scores (visual analogue scale and Western Ontario and McMaster Universities Osteoarthritis Index). No difference was found for the biomarkers between the two groups, with one exception. Both baseline and area under the curve per month COMP concentrations were significantly higher in the TFJ than the PFJ group (P<0.01).

CONCLUSIONS

The reduced serum COMP in PFJ disease compared with TFJ OA could be due to small articular cartilage volume in the latter or to a qualitative difference in cartilage metabolism.

A comparison of the semiflexed (MTP) view with the standing extended view (SEV) in the radiographic assessment of knee osteoarthritis in a busy routine X-ray department

OBJECTIVE

To compare the reproducibility of the standing extended view (SEV) (also known as the standing anteroposterior view) with the semiflexed, postero-anterior view [the 'metatarsophalangeal' (MTP)] view for assessing joint space width (JSW) and osteophytes in osteoarthritis of the knee when used in a busy routine X-ray department.

METHODS

Forty-seven patients (24 men) had both SEV and MTP views taken on the same day in a busy National Health Service radiography department. Repeat views were taken as entirely separate procedures some time over the following 2 weeks, in the same department and with no special arrangements for the selection of radiographers, time of day, or X-ray machine. The first 24 patients had second views in the SEV position whilst the remaining 23 had second MTP views. Radiographs were read independently by two experienced observers who measured JSW with a transparent ruler to the nearest 0.5 mm at the narrowest point in both medial and lateral compartments of the tibiofemoral joint in both knees. Osteophytes were graded 0-2 according to a standard atlas. Ten SEV and 10 MTP radiographs selected randomly were re-read by one observer.

RESULTS

Mean (95% confidence interval) JSW in the medial compartment measured on SEV radiographs was 3.54 mm (3.08, 3.99) and on MTP radiographs it was 2.80 mm (2.37, 3.23); in the lateral compartment it was 6.04 mm (5.71, 6.37) when measured on SEV radiographs and 5.47 mm (5.09, 5.85) on MTP radiographs. The estimated variances for the medial compartment were 2.0 mm2 for SEV and 0.2 mm2 for MTP (P < 0.001) and for the lateral compartment 1.4 mm2 for SEV and 0.5 mm2 for MTP (P < 0.001). The proportion of radiographs for which there was disagreement between observers regarding osteophyte grade was not statistically different between SEV and MTP views (SEV, medial 40%, lateral 44%; MTP, medial 39%, lateral 39%).

CONCLUSIONS

Even when radiographs are taken in a busy National Health Service radiography department, measurement of JSW from the MTP view is more reproducible than from the SEV view, the MTP view gives a slightly lower measurement of JSW, and there is no advantage in using either view in recording osteophyte grade. We recommend the wider adoption of the MTP method.

Identification of a nonframeshift 84-bp deletion in exon 13 of the cystic fibrosis gene

Cystic fibrosis (CF) is the most frequent autosomal recessive inherited disorder in Caucasian populations. The disease is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. We have identified an 84-bp deletion in exon 13 of the CFTR gene, detected by DNA amplification and direct sequencing of 500 bp of the 5' end of exon 13. The deletion was in the maternal allele of a CF patient bearing the delta F508 deletion in the father's allele. The same 84-bp deletion could also be detected in the patient's mother. The deletion spanned from a four-A cluster in positions 1949-1952 to another four-A cluster in positions 2032-2035, including 84 bp which correspond to codons 607-634 (1949del84). The reported mutation would result in the loss of 28 amino acid residues of the R domain of the CFTR protein.